Journal Article

Interictal diffusion MRI in partial epilepsies explored with intracerebral electrodes

Lionel Thivard, Claude Adam, Dominique Hasboun, Stéphane Clémenceau, Edouard Dezamis, Stéphane Lehéricy, Didier Dormont, Jacques Chiras, Michel Baulac and Sophie Dupont

in Brain

Published on behalf of The Guarantors of Brain

Volume 129, issue 2, pages 375-385
Published in print February 2006 | ISSN: 0006-8950
Published online December 2005 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awh709
Interictal diffusion MRI in partial epilepsies explored with intracerebral electrodes

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Patients with refractory partial seizures may benefit from epilepsy surgery. However, invasive investigations are often needed to define the precise location and limits of the epileptogenic zone (EZ). In this study, we asked whether diffusion tensor imaging (DTI) might provide a non-invasive alternative to locate the EZ or at least provide insights to help place intracerebral electrodes for stereo-electroencephalography (SEEG). Whole brain DTI and voxel-based analysis (SPM99) was used to assess diffusion properties objectively in 16 epilepsy patients investigated with SEEG. Epilepsy was symptomatic in two patients and cryptogenic in the 14 remaining patients. The suspected onset of seizures was temporal in 10 patients, frontal in 2 and occipital in 4. Individual maps of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated and compared to a database of 40 healthy volunteers. Thirteen of 16 patients exhibited diffusion abnormalities. ADC abnormalities were better correlated with SEEG data than FA abnormalities which were usually located at a distance or in the white matter. A significant increase in ADC (P < 0.01) was found in 11 patients and was located in the regions explored with depth electrodes in 7 of them. Surgery outcome was available in 3 of these 7 patients (2 were seizure free and 1 not). DTI specificity was better in extratemporal lobe epilepsy (83%) than in temporal lobe epilepsy (20%). When abnormalities concurred with the SEEG data, the concordance was optimal between the localization of the diffusion abnormalities and the irritative zone defined by SEEG. These encouraging, preliminary results, suggest that DTI examinations may provide accurate spatial data on the location and extent of the epileptogenic network in extratemporal lobe epilepsies.

Keywords: partial epilepsies; diffusion tensor imaging; stereo-electroencephalography; irritative zone; ADC = apparent diffusion coefficient; DTI = diffusion tensor imaging; EZ = epileptogenic zone; FA = fractional anisotropy; IZ = irritative zone; OZ = onset zone; SZ = spreading zone; SEEG = stereo-electroencephalography; SPECT = single photon emission computed tomography

Journal Article.  6363 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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